Common Fields
Each VCB has a number of common fields, as follows:
- opcode
- Verb operation code: an identifying field containing the name of the verb.
- format
- Identifies the format of the VCB. The value that this field must be set to in order to specify the current version of the VCB is documented individually under each verb.
- primary_rc
- Primary return code. Possible values for each verb are listed in the following sections.
- secondary_rc
- Secondary return code. This supplements the information provided by the primary return code. Possible values for each verb are listed in the following sections. Some VCBs also contain the following fields.
- opext
- Verb extension code. This supplements the information provided by the verb operation code. If the verb signal is to be processed in nonblocking mode, the flag AP_NON_BLOCKING must be set. In the signals described below these common fields are included, but not explained individually.
- TP Identifiers
- An 8-byte transaction program identifier is assigned to each active
transaction program. This identifier is assigned by Personal Communications.
The transaction program identifier is used to route TP_ENDED verbs and as a correlator on conversation verbs.
The verb control blocks for each signal are described in the following section.